The goal of the Analytical Cytometry Core (ACC) is to provide leading-edge equipment and experienced operators to measure properties of, and isolate, cells and their components, and present the data for internal analysis and external review. Flow cytometry instrumentation in this core resource includes (1) high speed cell sorter (MoFlo) and (2) analytical cytometers (Cyan and FacsCalibur). Flow cytometry instrumentation provides investigators with the tools to analyze and isolate cells at speeds of up to 35,000 cells/second based on multiple fluorescent labels and light scatter properties with high yield (up to 90% based on speed) and extreme purity (99%). Owing to the capability to sort for four populations at a time on multiple parameters, the logistics and cost for the investigators are substantially reduced. A new high throughput plate sampler for the Cyan analyzer provides rapid screening capacity to investigators with large compound libraries who use flow cytometric analysis in compound identification;the addition of a Laser Scanning Cytometer (LSC) has expanded the analytical capacity offered by the ACC to include quantitative tissuebased fluorescence microscopy. This instrumentation collects both listmode fluorescence data and microscopic images and provides users with the capacity to correlate quantitative fluorescent data with qualitative microscopic images on large tissue sections. The LSC is run by specially trained users and managed by a dedicated operator. ACC instrumentation is subject to weekly quality control assessment and routine preventive maintenance and calibration. Data generated in the Core is available through the BRI-net server for further analysis and preparation for presentation or publication. Network-based data processing software is offered by the core and a Laboratory Information Management System (LIMS) is being developed to help track experiment-related meta data and archived file retrieval. During FY 2006, the ACC was used by 44 Cancer Center members from all 5 programs and 3 non-aligned members (64% peer-reviewed usage). Annual budget for this core is $401,799 (43% institutional, 40% user fees);17% ($70,100) is requested from the CCSG.